1. Field of the Invention
The invention relates to a luminaire, in particular an arm-mounted spotlight or a picture light, having a long slim stem as a boom, at whose one end a lighting head is provided and at whose other end fixing elements are provided.
2. Description of the Prior Art
Luminaires of this type are either mounted permanently on the wall, which is the case in conventional picture lights, or are used as arm-mounted spotlights on exhibition stands, fixing elements which, in particular, permit fixing to the upper edge of supporting elements being expedient. A picture light of the type mentioned at the beginning is disclosed, for example, by the German Registered Design specification 29707541.
General requirements on such luminaires relate both to their form and to their function. A particularly long slim stem is desired, which lends to the luminaires a visible lightness; the lighting head should be fixed to this stem in such a way that its position can be changed around the stem in a simple way. As far as the fixing elements are concerned, in particular in the case of an arm-mounted spotlight, the point is that these permit simple adaptation to different wall thicknesses of a supporting element, in particular a dividing wall, a partition wall, a room divider or the like.
Accordingly, the object of the present invention is to design the fixing elements both for the lighting head and also for fixing the luminaire as a whole in such a way that they are simple to handle and can be used universally.
According to the invention, this object is achieved, in a luminaire of the type mentioned at the beginning, as claimed in the defining part of claim 1 or claim 2.
In this way, it is very simply possible not only to fix the luminaire as such, in that clamping elements are brought into contact with a supporting element from both sides; clamping elements present on the lighting head itself also permit the simple adjustment of the lighting head along the stem, specifically both in the longitudinal direction and by rotating it about the stem, care having simply to be taken that the lighting head is connected flexibly to a power source via an electric cable. A particularly expedient cable connection provides for the stem to be formed as a hollow tube through which the cable is routed, so that said cable is connected to the lighting head at one end of the stem and, at the other end, ends with a power plug.
In the embodiment with a clamping sleeve, the clamping is produced by simply pivoting the finger grip, the finger grip permitting a pivoting lever with a clamping profile to be operated and said profile embracing the two flanges from the outside in such a way that said flanges are increasingly moved toward each other as they are pivoted further, until the clamping position is reached. Because the flanges are moved together, the clamping sleeve is clamped around the stem until the clamping position of the clamping element has been implemented. In this position, the clamping element can be used, for example, as a stop against one side of a supporting element. A further clamping element forms the stop from the other side of the supporting element. The two clamping elements together therefore hold the luminaire on the upper edge of the supporting element. In this case, it is advantageous if the stem has a circular cross section, but is deformed ovally in the area of the clamping sleeves. This permits an additional antirotation safeguard of the stem within the clamping sleeves to be achieved. Nor does the luminaire rotate either when the lighting head is firmly clamped at the other end of the stem, pivoted toward the side.
In particular for fixing the lighting head, the design variant as claimed in claim 2 can be advantageous, in which at least two clamping elements are biased into the closed position against the stem by means of spring force, finger grips being provided on the clamping elements in such a way that when the finger grips are pressed together the clamping elements open.
A special clamping or opening mechanism is rendered superfluous in the abovementioned variant by the fact that in each case a clamping element is connected to a half shell of a sheet metal shield of the lighting head, and that the half shells can be operated, by means of the finger grips and counter to the spring force, to loosen the clamp connection.
In this variant, another preferred refinement provides for the half shells to be loaded in a spread position, by spring means arranged between them, in such a way that when the finger grips are operated the half shells are moved together but the clamping elements are moved apart.